i dont work offshore, but i do go offshore every so often if that makes sense. health and safety is probably the no1 concern thesedays, mess up on that and it usually means end of story (on uk rigs. yank rigs are a different story from what i hear). bosiet is also required (basic offshore training) for uk, if you want to work on norwegian rigs you'll need another qualification. see this website for courses http://www.hota.org/training.aspx?section=1
like rikos said, the money is generally good. if you're single the 2wks on 2wks off rota is no problem or if you aint fussed about the missus.